CPR-only survivors of out-of-hospital cardiac arrest: implications for out-of-hospital care and cardiac arrest research methodology.

STUDY OBJECTIVE: There is little evidence that cardiopulmonary resuscitation (CPR) alone may lead to the resuscitation of cardiac arrest victims with other than respiratory causes (eg, pediatric arrest, drowning, drug overdose). The objective of this study was to identify out-of-hospital cardiac arrest survivors resuscitated without defibrillation or advanced cardiac life support. METHODS: This observational cohort included all adult survivors of out-of-hospital cardiac arrest of a cardiac cause from phases I and II of the Ontario Prehospital Advanced Life Support Study. During the study period, the system provided a basic life support/defibrillation level of care but no advanced life support. CPR-only patients were patients determined to be without vital signs by EMS personnel who regained a palpable pulse in the field with precordial thump or CPR only and then were admitted alive to the hospital. Six members of a 7-member expert review panel had to rate the patient as either probably or definitely having an out-of-hospital cardiac arrest, and a rhythm strip consistent with a cardiac arrest rhythm had to be present to be considered a patient. Criteria considered were witness status, citizen or first responder CPR, CPR duration, arrest rhythm and rate, and performance of precordial thump. RESULTS: From January 1, 1991, to June 30, 1997, 9,667 patients with out-of-hospital cardiac arrest were treated. The overall survival rate to hospital discharge was 4.6%. There were 97 apparent CPR-only patients admitted to the hospital. Application of the inclusion criteria yielded 24 CPR-only patients who had true out-of-hospital cardiac arrest and 73 patients judged not to have cardiac arrest. Of the 24 true CPR-only patients admitted to the hospital, 15 patients were discharged alive, 10 patients were witnessed by bystanders, and 7 patients were witnessed by EMS personnel. The initial arrest rhythm was pulseless electrical activity in 9 patients, asystole in 12 patients, and ventricular tachycardia in 3 patients. One patient with ventricular tachycardia converted to sinus tachycardia with a single precordial thump. CONCLUSION: CPR-only survivors of true out-of-hospital cardiac arrest do exist; some victims of out-of-hospital cardiac arrest of primary cardiac cause can survive after provision of out-of-hospital basic life support care only. However, many patients found to be pulseless by means of out-of-hospital evaluation likely did not have a true cardiac arrest. This has implications for the survival rates of most, if not all, previous cardiac arrest reports. Survival rates from cardiac arrest may actually be lower if one excludes survivors who never had a true arrest. The absence of vital signs by out-of-hospital assessment alone is not adequate to include patients in research reports or quality evaluations for cardiac arrest.

The Ontario Prehospital Advanced Life Support (OPALS) study Part II: Rationale and methodology for trauma and respiratory distress patients. OPALS Study Group.

The Ontario Prehospital Advanced Life Support (OPALS) Study represents the largest prehospital study yet conducted, worldwide. This study will involve more than 25,000 cardiac arrest, trauma, and critically ill patients over an 8-year period (1994-2002). The current article, Part II, describes in detail the rationale and methodology for major trauma and respiratory distress patients and for an economic evaluation of Advanced Life Support (ALS) programs in the OPALS Study. The OPALS Study, using a rigorous controlled methodology and a large sample size, should clearly indicate the benefit in trauma and respiratory distress patient survival and morbidity that results from the widespread introduction of prehospital ALS programs to communities of many different sizes. [Stiell IG, Wells GA, Spaite DW, Nichol G, O'Brien B, Munkley DP, Field BJ, Lyver MB, Luinstra LG, Dagnone E, Campeau T, Ward R, Anderson S, for the OPALS Study Group: The Ontario Prehospital Advanced Life Support (OPALS) Study Part II: Rationale and methodology for trauma and respiratory distress patients.

Improved out-of-hospital cardiac arrest survival through the inexpensive optimization of an existing defibrillation program: OPALS study phase II. Ontario Prehospital Advanced Life Support.

CONTEXT: Survival rates for out-of-hospital cardiac arrest are low; published survival rates in Ontario are only 2.5%. This study represents phase II of the Ontario Prehospital Advanced Life Support (OPALS) study, which is designed to systematically evaluate the effectiveness and efficiency of various prehospital interventions for patients with cardiac arrest, trauma, and critical illnesses. OBJECTIVE: To assess the impact on out-of-hospital cardiac arrest survival of the implementation of a rapid defibrillation program in a large multicenter emergency medical services (EMS) system with existing basic life support and defibrillation (BLS-D) level of care. DESIGN: Controlled clinical trial comparing survival for 36 months before (phase I) and 12 months after (phase II) system optimization. SETTING: Nineteen urban and suburban Ontario communities (populations ranging from 16 000 to 750 000 [total, 2.7 million]). PATIENTS: All patients who had out-of-hospital cardiac arrest in the study communities for whom resuscitation was attempted by emergency responders. INTERVENTIONS: Study communities optimized their EMS systems to achieve the target response interval from when a call was received until a vehicle stopped with a defibrillator of 8 minutes or less for 90% of cardiac arrest cases. Working both locally and provincially, communities implemented multiple measures, including defibrillation by firefighters, base paging, tiered response agreements with fire departments, continuous quality improvement for response intervals, and province-wide revision and implementation of standard dispatch policies. All response times were obtained from a central dispatch system. MAIN OUTCOME MEASURE: Survival to hospital discharge. RESULTS: The 4690 cardiac arrest patients studied in phase I and the 1641 in phase II were similar for all clinical and demographic characteristics, including age, sex, witnessed status, rhythm, and receipt of bystander cardiopulmonary resuscitation. The proportion of cases meeting the 8-minute response criterion improved (76.7% vs 92.5%; P<.001) as did most median response intervals. Overall survival to hospital discharge for all rhythm groups combined improved from 3.9% to 5.2 % (P = .03). The 33% relative increase in survival represents an additional 21 lives saved each year in the study communities (approximately 1 life per 120000 residents). The charges were estimated to be US $46900 per life saved for establishing the rapid defibrillation program and US $2400 per life saved annually for maintaining the program. CONCLUSION: An inexpensive, multifaceted system optimization approach to rapid defibrillation can lead to significant improvements in survival after cardiac arrest in a large BLS-D EMS system.

Modifiable factors associated with improved cardiac arrest survival in a multicenter basic life support/defibrillation system: OPALS Study Phase I results. Ontario Prehospital Advanced Life Support.

STUDY OBJECTIVES: This study was conducted to identify modifiable factors associated with survival for prehospital cardiac arrest in a large, multicenter EMS system with basic life support/defibrillation (BLS-D) level of care. METHODS: This observational cohort study constitutes Phase I of the 3-phase Ontario Prehospital Advanced Life Support (OPALS) Study. Included were all adults who had cardiac arrest before EMS arrival in 21 urban/suburban communities that operate under the jurisdiction of 1 ambulance services branch, have 911 telephone service, and provide ambulance defibrillation but no prehospital advanced life support (ALS). Central dispatch and ambulance records were reviewed according to the Utstein guidelines. Associations between multiple patient and EMS factors and survival to discharge were assessed by univariate then stepwise logistic regression analyses. RESULTS: From January 1, 1991, to January 31, 1995, 5,335 eligible patients were treated. Of these, 46.8% of cardiac arrests were witnessed by citizens, 14.5% received bystander CPR, 25.6% received CPR by fire or police, and 38.2% had an initial rhythm of ventricular fibrillation/ventricular tachycardia (VF/VT). The mean interval from call received to vehicle stopped was 6.7 minutes. Survival was 3.5% overall and 8.8% for VF/VT. Multivariate analysis found the following factors to be independently associated with survival (odds ratio with 95% confidence intervals): age.81 (. 73,.89), bystander-witnessed arrest 4.05 (2.78, 5.90), bystander CPR 2.98 (2.07, 4.29), CPR by fire or police 2.20 (1.46, 3.31), and response interval call received to vehicle stopped.76 (.71,.82). CONCLUSION: This represents the largest multicenter BLS-D study of prehospital cardiac arrest yet conducted and clearly indicates that patient survival may be improved by optimization of EMS response intervals, bystander CPR, as well as first-responder CPR by fire or police.

The Ontario Prehospital Advanced Life Support (OPALS) Study: rationale and methodology for cardiac arrest patients.

The Ontario Prehospital Advanced Life Support Study represents the largest prehospital study yet conducted, worldwide. This study will involve more than 25,000 cardiac arrest, trauma, and critically ill patients over an 8-year period. The study will evaluate the incremental benefit of rapid defibrillation and prehospital Advanced Cardiac Life Support measures for cardiac arrest survival and the benefit of Advanced Life Support for patients with traumatic injuries and other critically ill prehospital patients. This article describes the OPALS study with regard to the rationale and methodology for cardiac arrest patients.